Always double-check your itinerary

I spent the last few days attending a conference in San Francisco.  The conference was Friday through Sunday.  I knew when I purchased my airline ticket the dates of the conference.  Imagine my surprise when I received an email, shortly after midnight Saturday morning, informing me that it was time to check-in for my flight.  I knew this couldn’t be correct because my flight wasn’t scheduled to leave until 12:35 a.m. May 18 or so I thought.  After a conversation with the airline’s customer service department, just before 1 a.m., I realized that I had purchased the ticket for the wrong date.  Now, I’m not going to sit here and blame the website or anything else.  I bought the ticket and failed to verify the date of the return trip.  So, learn from me to always double-check your itinerary before you click the purchase button.  Otherwise, have fun booking a one-way ticket back home!

Using OAUTH for Delphi

Before attempting to use OAUTH, you must obtain a developer key and secret from the service provider.  In the sample code provided in this article, I have removed my developer key and secret.  No other code modifications have been made.

Step 1 – Request request token (step A in diagram)

procedure TForm1.RqsBtnClick(Sender: TObject);
var
URL: string;
endpos: integer;
begin
Key := ‘http://www.myspace.com/developerkey’;
Secret := ‘developersecret’;
URL := ‘http://api.myspace.com/request_token’;
// Create all objects
Consumer := TOAuthConsumer.Create(Key, Secret);
HMAC := TOAuthSignatureMethod_HMAC_SHA1.Create;

ARequest := TOAuthRequest.Create(URL);

ARequest := ARequest.FromConsumerAndToken(Consumer, nil, URL);
ARequest.Sign_Request(HMAC, Consumer, nil);
HTTPStream := TStringStream.Create(”);
URL := URL + ‘?’ + ARequest.GetString;
Response := idHTTP1.Get(URL);

endpos := AnsiPos(‘&oauth_token_secret=’, Response);
oauth_token := ”;
oauth_token := Copy(Response, 13, endpos-13);
Response := Copy(Response, endpos, Length(Response));

oauth_token_secret := Copy(Response, 21, Length(Response));
Token := TOAuthToken.Create(oauth_token, oauth_token_secret);
end;

The service provider responds by sending a token and token secret, which is parsed from the Response variable.

Step 2 – Authorize (Step C in diagram)

procedure TForm1.AuthBtnClick(Sender: TObject);
var
Callback_URL, URL :string;
begin
URL := ‘http://api.myspace.com/authorize’;
Callback_URL := ‘http://www.chuckbeasley.com’;
URL := URL + ‘?’ + ‘oauth_token=’ + oauth_token + ‘&’ + ‘oauth_token_secret=’ + oauth_token_secret +
‘&oauth_callback=’ + TOAuthUtil.urlEncodeRFC3986(Callback_URL);
EmbeddedWB1.Navigate(URL);
end;

The token, token secret, and call back URL are appended to the URL.  The service provider obtains user authorization and directs the consumer to the call back URL.

Step 3 – Request access token (Step E in diagram)

procedure TForm1.AccBtnClick(Sender: TObject);
var
endpos: integer;
URL: string;
begin
URL := ‘http://api.myspace.com/access_token’;
Consumer := nil;
Consumer := TOAuthConsumer.Create(Key, Secret, ‘http://www.chuckbeasley.com’);
ARequest.HTTPURL := URL;
ARequest := ARequest.FromConsumerAndToken(Consumer, Token, URL);
ARequest.Sign_Request(HMAC, Consumer, Token);
URL := URL + ‘?’ + ARequest.GetString;
Response := idHTTP1.Get(URL);
endpos := AnsiPos(‘&oauth_token_secret=’, Response);
oauth_token := ”;
oauth_token := Copy(Response, 13, endpos-13);
Response := Copy(Response, endpos, Length(Response));

oauth_token_secret := Copy(Response, 21, Length(Response));
Token := TOAuthToken.Create(oauth_token, oauth_token_secret);
end;

The service provider responds by sending an access token and token secret, which is parsed from the Response variable.

Step 4 – Access protected resources (Step G on diagram)

procedure TForm1.AccRscClick(Sender: TObject);

procedure process(o: ISuperObject);
var
f: TSuperObjectIter;
i: Integer;
begin
case ObjectGetType(o) of
stObject:
begin
Memo1.Lines.Add(‘{‘);
if ObjectFindFirst(o, f) then
repeat
keypair := f.key;
process(f.val)
until not ObjectFindNext(f);
ObjectFindClose(f);
Memo1.Lines.Add(‘}’);
end;
stArray:
begin
Memo1.Lines.Add(‘[');
for i := 0 to o.AsArray.Length - 1 do
process(o.AsArray.O[i]);
Memo1.Lines.Add(‘]’);
end;
stString:
begin
keypair := keypair + ‘:’ +(UTF8Decode(o.AsString));
Memo1.Lines.Add(keypair);
end;
stNull:
Memo1.Lines.add(‘nil’);
else
Memo1.Lines.add(o.AsString);
end;
end;
var
json: ISuperObject;
StringList: TStringList;
URL: string;
begin
URL := ‘http://api.myspace.com/v2/people/40250975/@friends?count=10000&format=json’;
Consumer := nil;
Consumer := TOAuthConsumer.Create(Key, Secret, ‘http://www.chuckbeasley.com’);
ARequest.HTTPURL := URL;
ARequest := ARequest.FromConsumerAndToken(Consumer, Token, URL);
ARequest.Sign_Request(HMAC, Consumer, Token);
URL := URL + ‘&’ + ARequest.GetString;
Response := idHTTP1.Get(URL);

StringList := TStringList.Create;
StringList.Add(Response);

json := TSuperObject.Create(stObject);
json.Merge(Response);
json := json.O['entry'];
Memo1.Lines.Clear;
process(json);
end;

This step assumes that the profile owner has authorized the application to access its protected data.  That can be performed by adding the application to the profile.

OAUTH for Delphi is available via SVN:   http://oauthdelphi.svn.sourceforge.net/.

Catching up with technology

So, I’ve finally decided to write an entry in my blog.  In less than 2 weeks, I’ve join Twitter and begun blogging.  I’m not exactly sure what I’ll find to write about, but I’ll make it interesting.  Check back from time to time to see what things I find on the ‘net.